JPH0458491B2 - - Google Patents

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD The present invention relates to polyurethane (hereinafter sometimes referred to as polyester polyurethane) made from polyester polyol and polyisocyanate. BACKGROUND ART Conventionally, polyurethane has been produced by reacting polyols and polyisocyanates, and if desired, using low molecular weight compounds having active hydrogen atoms as raw materials. Recently, as polyols, acid components such as aliphatic dicarboxylic acids such as succinic acid, glutaric acid, adipic acid, azelaic acid, and sebacic acid, and relatively small number of carbon atoms such as ethylene glycol, propylene glycol, and 1,4-butanediol have been developed. Diol (hereinafter referred to as
_C2-4 diol), or polyalkylene glycol, neopentyl glycol, 1,5-pentanediol, derived therefrom;
1,6-hexane glycol etc. with 5 to 6 carbon atoms
Polymer polyols such as polyester polyols obtained by condensation polymerization of diol components such as diols (hereinafter sometimes referred to as _C5-6 diols) have come to be used. Problems to be Solved by the Invention However, conventional polyurethanes whose polymeric polyols are polyester polyols obtained using _C2-4 diols have poor hydrolysis resistance and mold resistance, and as a result, they cannot be easily exposed to high temperatures and high humidity. Under certain conditions, the surface becomes sticky or cracks occur in a relatively short period of time, which severely limits its use. On the other hand, polycaprolactone polyol or 1,
Polyurethanes using polyester polyols obtained from 6-hexanediol, neopentyl glycol, and adipic acid as polyol components are known, but these polyurethanes also do not have satisfactory hydrolysis resistance, and their resistance is poor. It cannot be said that it has excellent mold resistance. Furthermore, the polyurethane had the following problems. That is, when the polyurethane has low hardness,
The problem is that it is highly sticky despite its desirable texture, which is in great demand in various fields.
There are various problems in the production of the soft segment due to crystal hardening of the soft segment over time and deterioration of physical properties, and the reality is that a product of a satisfactory level has not yet been obtained. Therefore, when producing thermoplastic polyurethane pellets with low hardness, and furthermore when producing molded products such as films, tubes, and belts from the pellets, problems in terms of tackiness are particularly likely to occur. In view of the above facts, the present inventors have developed a polyester polyurethane that has excellent hydrolysis resistance and mold resistance, does not cause crystal whitening or hardening even with a flexible polyurethane composition, and is non-adhesive. We conducted extensive research with the aim of providing a manufacturing method. Means for Solving the Problems According to the present invention, the above object is to provide a method for producing polyurethane from a high molecular weight polyester polyol and a polyisocyanate, in which the polyester polyol has the formula Contains a structural unit () represented by the formula as a dicarboxylic acid-based unit (In the formula, n represents an integer from 1 to 10) Structural unit () and formula (In the formula, Ar represents an arylene group having 6 to 10 carbon atoms.) The molar ratio of structural unit ()/structural unit () is 2/8 to 7/
This is achieved by a method for producing polyurethane, which is characterized in that it uses a polyester polyol containing a proportion of 3. The polyester polyols used in the present invention are polyester diols, polyester triols, and polyester tetraols containing the above-mentioned structural units (), (), and (), and the diols and structural units () that can produce the structural units ().
It is produced by condensation polymerization of a mixture of an aliphatic dicarboxylic acid capable of producing the structural unit () and an aromatic dicarboxylic acid capable of producing the structural unit (). A typical diol that can form the structural unit () is 3-methyl-1,5-pentanediol, which has the formula It is indicated by. A part of the diol represented by the above formula () may be replaced with another diol within a range that does not impair the intended purpose of the present invention. Examples of diols that can be substituted include those having 2 carbon atoms, such as ethylene glycol, propylene glycol, 1,4-butanediol, 1,6-hexanediol, diethylene glycol, and neopentyl glycol.
-12 diols may be mentioned, but it goes without saying that those with a large number of carbon atoms are preferable in consideration of hydrolysis resistance. Furthermore, it is also permissible to use a small amount of polyhydric alcohol such as trimethylolpropane, glycerin, or pentaerythritol in combination with the above diol, and improvement in heat resistance and oil resistance can be expected. In any case, it is desirable that the structural unit () accounts for 50 mol% or more, preferably 70 mol% or more of the diol component. On the other hand, structural units based on dicarboxylic acid components are
formula Structural unit and formula represented by It is a structural unit represented by . In the above formula (), n represents an integer of 1 to 10, and examples of aliphatic dicarboxylic acids that can produce the above formula () include succinic acid, glutaric acid, adipic acid, azelaic acid, sebacic acid, etc. It will be done. These dicarboxylic acids may be used not only alone but also in combination of two or more. In addition, in the above formula (), Ar is a phenylene group or a naphthylene group which may have a substituent having 6 to 10 carbon atoms, and specific examples of aromatic dicarboxylic acids that can produce the above formula () are: Terephthalic acid, isophthalic acid, orthophthalic acid, 1,5-naphthalene dicarboxylic acid,
Examples include 2,5-naphthalene dicarboxylic acid, 2,6-naphthalene dicarboxylic acid, and mixtures thereof in arbitrary proportions. Further, as the above-mentioned aromatic dicarboxylic acid, an alkyl ester thereof can also be used. In the polyester polyol, the molar ratio of structural unit ()/(total of structural unit () and structural unit ()) may be such that the molecular terminal of the produced polyester polyol becomes a hydroxyl group. Moreover, it is important that the molar ratio of structural unit ( )/structural unit ( ) is within the range of 2/8 to 7/3. If the molar ratio is 7/3 or more, the intended purpose of the present invention, which is to provide non-stick properties and improve hydrolysis resistance, will not be achieved;
The following cases are undesirable because the low-temperature properties of the resulting polyurethane become poor, and furthermore, the elongation becomes low, resulting in disadvantages. In the present invention, there is no particular restriction on the method for producing polyester polyol, and known polyester condensation polymerization means can be applied. For example, the above compounds capable of producing the structural units (), () and () are charged in a desired ratio, esterified or transesterified at 150 to 250°C in the presence of an esterification and/or transesterification catalyst, and The reaction product obtained in this way was further heated under high vacuum for 200 to 300 minutes.
It can be produced by polycondensation at ℃. In this case, it is possible to simultaneously prepare the three components as described above to obtain a copolymerized polyester polyol, but the following method may also be adopted. In other words, when producing polyurethane by separately synthesizing a polyester polyol containing structural units () and () and a polyester polyol containing structural units () and (), the molar ratio of structural unit ()/structural unit () 2/8~7/
It is also possible to use a mixture of the above two so as to satisfy condition 3. The polyester polyol used in the present invention generally has a molecular weight of about 500 to 5,000, preferably 800 to 3,000. When the polyurethane produced using the polyester polyol used in the present invention is used as an adhesive, the polyester polyol preferably has a molecular weight of 3,000 to 50,000, preferably 500 to 30,000. It goes without saying that it is preferable that the acid value and water content are as low as possible. The polyisocyanate used in the present invention includes known aliphatic, alicyclic, and aromatic organic polyisocyanates containing two or more isocyanate groups in the molecule, but especially 4,4'-diphenyl Methane diisocyanate, p-phenylene diisocyanate, tolylene diisocyanate, 1,5-naphthylene diisocyanate, xylylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, 4,
In addition to diisocyanates such as 4'-dicyclohexylmethane diisocyanate, there are also trimethylolpropane and triisocyanate in which 3 moles of tolylene diisocyanate is added to 1 mole of glycerin. Further, in the present invention, a suitable chain extender may be used as desired, and the chain extender includes a chain extender commonly used in the polyurethane industry, that is, a chain extender containing at least two hydrogen atoms capable of reacting with isocyanate. Compounds are included. For example, ethylene glycol, 1,4-butanediol, xylylene glycol, bishydroxyethoxybenzene, neopentyl glycol, 3,
Contains 3'-dichloro-4,4'-diaminodiphenylmethane, isophorone diamine, 4,4'-diaminodiphenylmethane, hydrazine, dihydrazide, trimethylolpropane, glycerin, and the like. As for the operating method for obtaining polyurethane, known urethanization reaction techniques are used.
For example, by mixing a high-molecular polyester polyol and a low-molecular compound having active hydrogen,
After preheating to 100°C, add polyisocyanate compounds in an amount such that the ratio of the number of active hydrogen atoms to NCO groups in these compounds is about 1:1, stir vigorously for a short time, and heat at about 50 to 150°C. You get it if you leave it alone. It can also be carried out via a urethane prepolymer. Polyisocyanate compounds are usually used in a very slight excess because they are affected by moisture and other factors. These reactions are carried out using dimethylformamide, diethylformamide, dimethylsulfoxide, dimethylacetamide, tetrahydrofuran, isopropanol, benzene, toluene,
One or two of ethyl cellosolve, trichlene, etc.
It can also be carried out in a solvent consisting of more than one species. In this case, it is convenient to set the concentration within the range of 10 to 40% by weight in order to obtain a product with a high molecular weight. The degree of polymerization of the obtained polyurethane is preferably within the range of 10,000 to 150,000 in terms of number average molecular weight. Next, some examples of uses of the polyurethane obtained by the present invention will be described. (1) Substantially linear thermoplastic polyurethane pellets are made, and elastomer products are produced by heating and melting the pellets and using methods such as injection molding, extrusion molding, and calendering. (2) mixing together a polymeric polyester polyol, an organic polyisocyanate, and a chain extender;
Alternatively, a high-molecular polyester polyol and an organic polyisocyanate are reacted in advance to produce a prepolymer having terminal isocyanate groups or terminal hydroxyl groups, and a chain extender or polyisocyanate is mixed with this to make a cast elastomer product or a paint, Used for adhesives, etc. (3) In the methods (1) and (2) above, a polyurethane solution obtained by dissolving polyurethane raw materials in a solvent to synthesize polyurethane or a polyurethane solution obtained by dissolving the obtained polyurethane in a solvent is used to produce synthetic leather. It is used as a coating agent and impregnating agent for artificial leather, fibers, etc., and as a texture control agent. (4) Dissolve the terminal isocyanate prepolymer in a solvent, add a chain extender, etc. to it to prepare a stable spinning stock solution, and produce elastic fibers from this stock solution by a wet method or a dry method. (5) Various additives such as a foaming agent are blended into a high-molecular polyester polyol, an organic polyisocyanate or a prepolymer having a terminal isocyanate group is added thereto, and the mixture is stirred at high speed to foam to produce a foam product. More specifically, the polyurethane of the present invention can be used in sheets, films, rolls, gears, solid tires, belts, hoses,
It is useful for tubes, vibration-proofing materials, packing materials, shoe soles (microcellular, etc.), artificial leather, fiber treatment agents, cushion materials, paints, adhesives, sealants, waterproofing agents, flooring materials, elastic fibers, etc. Effects In the present invention, polyurethane having excellent various properties can be obtained as described below, but the reason for this cannot be explained by a single reason and is not necessarily clear. However, if we organize and simplify the explanation, it can be estimated as follows. That is, since the polyurethane produced by the production method of the present invention contains a relatively long-chain diol-based structural unit ( ) and an aromatic dicarboxylic acid-based structural unit ( ) as structural units,
Excellent hydrolysis resistance. In addition, since it contains a structural unit () based on a diol with a side chain,
For example, crystallinity in the structural unit () based on terephthalic acid or the like can be suppressed, and furthermore, the soft segment will not crystallize even during the synthesis of low hardness polyurethane. In addition, it is non-adhesive because it contains an aromatic ring. Although the reason for the improvement in mold resistance is completely unknown, it is thought that the structural units (), (), and () are deeply involved. Examples Next, the present invention will be explained in more detail with reference examples, examples, and comparative examples. In the Examples and Comparative Examples, the hydrolysis resistance of polyurethane was determined by subjecting a 60μ thick polyurethane film to a hydrolysis acceleration test in hot water at 100°C for two weeks, and then placing the film in DMF (dimethylformamide). The retention rate of logarithmic viscosity measured after redissolution was also evaluated. In addition, regarding the evaluation of mold resistance, molded and processed thickness on glucose peptone agar culture medium
Attach a 200μ polyurethane film, inoculate with a mixed spore suspension of 5 types of mold, and store at 30℃ and humidity.
The cells were cultured at 90-95% and the state of surface deterioration was observed. In addition, this test includes Aspergillus niger, which is described in JIS Z2911-1960 mold resistance test.
ATCC9642, Penicillium luteum
ATCC9644, Rhizobus nigricans SN32,
Five types of molds were used: Trichoderma T-1 ATCC9645 and Chaetomium globosum ATCC6205. For tackiness, polyurethane is extruded
It was extruded into water at 200°C to form pellets, and the stickiness of the pellets was evaluated. When the pellets had stickiness, the pellets were stuck in a block shape, and the evaluation was rated as × if the degree of stickiness was large, △ if the pellets were stuck a little, and ○ if there was no stickiness at all and the pellets did not stick. The thermoplastic polyurethane pellets marked with ◯ do not have tackiness even when extruded into a film using a T-die, but those marked with × or △ were difficult to form into films. Regarding crystal whitening, a polyurethane film with a thickness of 60 μm was left for one week, and then the whitening state of the film was observed, and those that turned white were expressed as x, and those that remained transparent were expressed as ○. Low-temperature flexibility was evaluated by coating and drying a polyurethane solution on an artificial leather substrate and measuring the bending resistance at -20°C (the thickness of the polyurethane film on the substrate was 20μ).
The bending resistance was tested using a bending tester with a stroke width (3 cm at the longest, 1 cm at the shortest) and a bending frequency of 8,600 times/hour. If there is no change after 100,000 cycles or more, it is marked with ○, if there is some damage, it is marked with △, and if the substrate is damaged to the extent that it is visible, it is marked with ×. Regarding hardness, follow the method of JIS-K6301. In addition, although the raw materials used in each table of Reference Examples, Examples, and Comparative Examples are shown with abbreviations, the relationship between the abbreviations and compounds is as follows (Table 1).

[Table] Reference example 1 (Production of polyester polyol) 3-methyl-1,5-pentanediol 317.2
g, 174 g of terephthalic acid and 146 g of adipic acid
(Molar ratio of 3MPD/TA/AD: 2.6/1/1) was esterified under normal pressure while passing nitrogen gas and distilling condensed water at a temperature of about 195°C. When the acid value of the polyester became about 1 or less, the degree of vacuum was gradually increased using a vacuum pump to complete the reaction. In this way, a polyester polyol (hereinafter referred to as polyester A) having a hydroxyl value of 56 and an acid value of 0.2 was obtained. This polyester A was liquid at room temperature and had a molecular weight of about 2,000. Reference Examples 2 to 11 Polyesters B to K were obtained in the same manner as in Reference Example 1 using the diol component and dicarboxylic acid component shown in Table 2 at the molar ratio of diol component to dicarboxylic acid component in Reference Example 1. Table 2 shows the molecular weight and acid value of the obtained polyester.

[Table] Example 1 Polyester A produced in Reference Example 1 was heated in vacuum.
Dry at 110°C, add 1,4-butanediol (chain extender) and 4,4'-diphenylmethane diisocyanate to the polyester A/
4,4'-diphenylmethane diisocyanate/
Molar ratio of 1,4-butanediol (in Table 3, X/
After mixing at a ratio of 1/2/1 (denoted as Y/Z), it is fed into a twin-screw extruder, and the
The polyurethane was melt-polymerized at .degree. C., and the melt-polymerized polyurethane was further cut in water to produce polyurethane pellets. Various performances of the obtained polyurethane were measured. The results are shown in Table 4. Examples 2 to 9 and Comparative Examples 1 to 7 Same as Example 1 except that the polyester polyol, polyisocyanate, and chain extender shown in Table 3 were used at the molar ratio (X/Y/Z) shown in Table 3. Polyurethane was obtained by the method. In addition, when bishydroxyethoxybenzene was used as a chain extender, it was heated and melted before use. Table 4 shows the performance of the obtained polyurethane.

【table】

[Table] Molar ratio of prolonging agents

[Table] Example 10 A polyester polyol with a molecular weight of 15,000 was obtained from 3-methyl-1,5-pentanediol, isophthalic acid and azelaic acid (IPA/AZ molar ratio: 2/1). 50 parts by weight of this polyester
After diluting with 10 parts by weight of ethyl acetate, 10 parts by weight of Coronate L manufactured by Nippon Polyurethane Co., Ltd. (a triisocyanate obtained by adding 3 moles of tolylene diisocyanate to 1 mole of trimethylolpropane) was added, and then diluted with 20 parts by weight of ethyl acetate. Diluted to a weight% solution, and using a laminator, laminated polyester film and polypropylene film (CPP, surface corona treated) together at a coating amount of 8 g/m ² at 40°C.
After curing and adhering for several days, the adhesive strength (tensile speed
300mm/min T-shaped peeling) was measured. 400g/15
It showed good adhesive strength of mm. Moreover, no whitening of the adhesive film was observed and the result was good. No mold growth was observed for 12 months, making it an excellent adhesive for food packaging laminated films, etc. Effects of the Invention The polyurethane obtained by the production method of the present invention has excellent hydrolysis resistance and mold resistance, and also exhibits flexibility even at low temperatures, yet does not cause crystal whitening or hardening, and Non-stick. In addition, in terms of mechanical properties, it is comparable to conventional polyurethane.

Claims (1)

[Claims] 1. A method for producing polyurethane from a high-molecular polyester polyol and a polyisocyanate, wherein the polyester polyol has the formula Contains a structural unit () represented by the formula as a dicarboxylic acid-based unit (In the formula, n represents an integer from 1 to 10) Structural unit () and formula (In the formula, Ar represents an arylene group having 6 to 10 carbon atoms.) The molar ratio of structural unit ()/structural unit () is 2/8 to 7/
A method for producing polyurethane, characterized in that a polyester polyol containing a polyester polyol in a ratio of 3 to 3 is used.